The development of the damage structure produced in (100) GaAs/Al0.6Ga0.4As/GaAs by 1 MeV Kr+ ion irradiation at 77 and 293 K has been investigated by RBS channeling and cross-sectional high-resolution TEM techniques. Following an implantation to a dose of 1014 ions cm-2 at 77 K, RBS channeling spectra indicate that the Al0.6Ga0.4 layer contained a high defect density and was possibly amorphous. Warming to room temperature resulted in a change in the channeling spectrum, which indicated that the damage in the Al0.6Ga0.4As layer had partially recovered. The degree of recovery was greatest at the GaAs/ Al0.6Ga0.4As interface, and decreased with increasing depth. TEM observations show the damage in the Al0.6Ga0.4As to be comprised of planar defects, the density of which increases with depth, and an amorphous layer at the bottom interface. This difference in the damage distribution is consistent with the asymmetry in the channeling spectrum. A model based on the depth variation of cascade density is proposed to account for the observations.